Systems for generating auxiliary electrical power  for jet aircraft propulsion systems

ABSTRACT

An aircraft jet propulsion system is disclosed. The aircraft jet propulsion system may comprise a thermoelectric generator array (“TEG” array) coupled to a portion of the aircraft jet propulsion system, wherein the TEG array converts heat energy to electrical energy, and supplies power to the aircraft jet propulsion system, wherein the electrical energy is supplied to a power supply. The aircraft jet propulsion system may comprise an alternator that generates less energy than is required to power the aircraft jet propulsion system. The TEG array may supplement the energy generated by the alternator. The energy generated by the TEG array and the energy generated by the alternator may be sufficient to power the aircraft jet propulsion system and/or the electrical energy generated by the TEG array may be sufficient to power to aircraft jet propulsion system.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of, claims priority to and thebenefit of, U.S. application Ser. No. 14/946,151 filed on Nov. 19, 2015and entitled “SYSTEMS FOR GENERATING AUXILIARY ELECTRICAL POWER FOR JETAIRCRAFT PROPULSION SYSTEMS,” which claims priority to and the benefitof, PCT/US2014/053190 filed on Aug. 28, 2014 and entitled “SYSTEMS FORGENERATING AUXILIARY ELECTRICAL POWER FOR JET AIRCRAFT PROPULSIONSYSTEMS,” which claims priority to and the benefit of, U.S. ProvisionalApplication No. 61/878,494 filed on Sep. 16, 2013 and entitled “SYSTEMSFOR GENERATING AUXILIARY ELECTRICAL POWER FOR JET AIRCRAFT PROPULSIONSYSTEMS.” All of the aforementioned applications are incorporated hereinby reference in their entirety.

FIELD

The present disclosure relates to electrical power, and moreparticularly, to an auxiliary electrical power system for use with a jetaircraft propulsion system.

BACKGROUND

Jet aircraft propulsion systems (e.g., a gas turbine engine coupled to anacelle) generate large amounts of heat energy. A variety of coolingsystems are available to cool these systems. For example, propulsionsystems may be cooled by air cooling systems, radiative cooling systems,and other like cooling systems.

SUMMARY

An aircraft jet propulsion system is disclosed. The aircraft jetpropulsion system may comprise a thermoelectric generator array (“TEGarray”) coupled to a portion of the aircraft jet propulsion system,wherein the TEG array converts heat energy to electrical energy. Theaircraft jet propulsion system may also comprise a TEG array thatconverts heat energy to electrical energy and supplies the electricalenergy to, a power supply. The power supply may supply power to theaircraft jet propulsion system. The aircraft jet propulsion system maycomprise an alternator that generates less electrical energy than theamount of electrical energy associated with the electrical needs of theaircraft jet propulsion system. The TEG array may supplement the energygenerated by the alternator. In various embodiments, the energygenerated by the TEG array and the energy generated by the alternatormay be sufficient to fulfill the electricity needs of the aircraft jetpropulsion system and/or the electrical energy generated by the TEGarray may be sufficient to fulfill the electricity needs of the aircraftjet propulsion system.

In various embodiments, the TEG array may be coupled to an exhaustportion of the aircraft jet propulsion system, and the exhaust portionmay comprise an exhaust nozzle. The TEG array may be coupled to any of:an outer surface of an inner fixed structure (“IFS”), an inner surfaceof a nacelle, between a heat blanket and an inner surface of a nacelle,to an outer surface of a heat blanket mounted to an inner surface of anacelle, an air inlet, an air inlet outboard of an anti-ice system, andthe like.

The TEG array may comprise a plurality of TEGs electrically coupled inseries and/or a plurality of sets of TEGs, each set electrically coupledin parallel. The TEG array may comprise six sets of TEGs, each setelectrically coupled in parallel. The TEG array may comprise six TEGscoupled in series. The TEG array may, in various embodiments, generatefrom about 20 Volts to about 50 Volts and from about 1 W to about 500 W.

A TEG array is disclosed. In various embodiments, the TEG array maycomprise a first set of thermoelectric generators coupled in seriesand/or a second set of TEGs coupled in series, wherein the first set ofTEGs and the second TEGs may be coupled in parallel.

BRIEF DESCRIPTION OF THE DRAWINGS

The subject matter of the present disclosure is particularly pointed outand distinctly claimed in the concluding portion of the specification. Amore complete understanding of the present disclosure, however, may bestbe obtained by referring to the detailed description and claims whenconsidered in connection with the drawing figures, wherein like numeralsdenote like elements.

FIG. 1 illustrates, in accordance with various embodiments, across-sectional view of a turbofan engine.

FIG. 2 illustrates, in accordance with various embodiments, across-sectional view of a TEG;

FIG. 3 illustrates, in accordance with various embodiments, a circuitdiagram of a TEG array;

FIG. 4 illustrates, in accordance with various embodiments, across-sectional view of an exhaust portion of a jet aircraft propulsionsystem equipped with a TEG array;

FIG. 5 illustrates, in accordance with various embodiments, a fan cowlanti-ice system of a jet aircraft propulsion system equipped with a TEGarray; and

FIG. 6 illustrates, in accordance with various embodiments, across-sectional view of an inner fixed structure of a jet aircraftpropulsion system equipped with a TEG array.

DETAILED DESCRIPTION

The detailed description of exemplary embodiments herein makes referenceto the accompanying drawings, which show exemplary embodiments by way ofillustration and their best mode. While these exemplary embodiments aredescribed in sufficient detail to enable those skilled in the art topractice the inventions, it should be understood that other embodimentsmay be realized and that logical, chemical and mechanical changes may bemade without departing from the spirit and scope of the inventions.Thus, the detailed description herein is presented for purposes ofillustration only and not of limitation. For example, the steps recitedin any of the method or process descriptions may be executed in anyorder and are not necessarily limited to the order presented.Furthermore, any reference to singular includes plural embodiments, andany reference to more than one component or step may include a singularembodiment or step. Also, any reference to attached, fixed, connected orthe like may include permanent, removable, temporary, partial, fulland/or any other possible attachment option. Additionally, any referenceto without contact (or similar phrases) may also include reduced contactor minimal contact.

As used herein, “aft” refers to the direction associated with the tail(e.g., the back end) of an aircraft, or generally, to the direction ofexhaust of the gas turbine. As used herein, “forward” refers to thedirection associated with the nose (e.g., the front end) of an aircraft,or generally, to the direction of flight or motion.

As described above, jet aircraft propulsion systems generate largeamounts of heat energy. A variety of cooling systems are available tocool these propulsion systems. For example, propulsion systems may becooled by air cooling systems, radiative cooling systems, and other likecooling systems. In operation, however, these cooling systems may bleedlarge amounts of heat energy away from the aircraft propulsion system,though the heat energy is largely dissipated as heat. Specifically,these systems may not recapture heat energy generated by the propulsionsystem during operation so that the heat energy may be harnessed foruseful work.

With reference to FIG. 1, an aircraft propulsion system 100 is shown andmay generally comprise a nacelle 102 comprising an inner fixed structure(“IFS”) 104. The aircraft propulsion system 100 may generally extendfrom forward to aft along the axis A-A′, with point A being forward ofpoint A′ and point A′ being aft of point A In flight, air from point Amay flow around and/or through aircraft propulsion system 100 in thedirection from point A to point A′. The nacelle 102 may define an outerairflow surface of the aircraft propulsion system 100. The nacelle 102may include an air inlet 114 through which air may enter aircraftpropulsion system 100. An anti-ice system (not shown, and which may heatthe air inlet to melt ice) may be disposed within the air inlet 114. TheIFS 104 may define an inner airflow surface of the aircraft propulsionsystem 100. The IFS 104 may be disposed coaxially to engine core 106.The engine core 106 may burn a hydrocarbon fuel in the presence ofcompressed air to generate exhaust gas 108. The exhaust gas 108 may beexpanded across a turbine 116 to drive turbofan 110 at the forwardportion of the aircraft propulsion system 100. The turbofan 110 mayrotate to generate bypass fan airflow 112 between an interior surface ofthe nacelle 102 and an exterior surface of the IFS 104.

With reference to FIG. 2, a thermoelectric generator (“TEG”) may becoupled to one or more portions of aircraft propulsion system 100 torecapture heat energy generated by aircraft propulsion system 100.Referring to FIG. 2, although TEGs may vary in the construction and/orcomposition, TEG 200 may generally comprise first substrate 202 and asecond substrate 204. The first substrate 202 may comprise any substratecapable of conducting heat, such as a metallic or ceramic wafer. Thesecond substrate 204 may comprise any substrate capable of conductingheat, such as a metallic or ceramic wafer. The first substrate 202 maybe in thermal contact with a heat source 206. Thermal contact, as usedherein, may mean that two objects may exchange heat. Heat may beexchanged by convection, conduction, and/or radiation. The secondsubstrate 204 may be in contact with heat sink 208 and/or, in general,with any material or surface that is configured to dissipate heat. Theheat source 206 may generate energy as heat, while the heat sink 208 mayabsorb and/or dissipate energy as heat.

A plurality of thermoelectric semiconductors 210 a-210 i may be situatedor laminated between the first substrate 202 and the second substrate204. Each thermoelectric semiconductor 210 a-210 i may comprise eitherof an n-type material (e.g., 210 a, 210 c, 210 e, 210 g, and 210 i) or ap-type material (e.g., 210 b, 210 d, 210 f, and 210 f). Eachthermoelectric semiconductor 210 a-210 i may be electrically coupledthrough a respective electrical interconnect 216 a-216 j. Thus, eachthermoelectric semiconductor 210 a-210 i may be thermally coupled inparallel and electrically coupled in series and together form TEG 200.

An n-type material may comprise a semiconductor doped with an electrondonating material or impurity. A p-type material may comprise asemiconductor doped with an electron accepting material or impurity. Anelectron donating impurity may contribute free electrons to thesemiconductor. These electrons may move within the semiconductor. Anelectron accepting impurity may contribute atoms capable of acceptingelectrons to the semiconductor. The absence of an electron in thevalence band of an electron accepting impurity may be referred to as a“hole.” A hole may function as charge carrier that may move within thesemiconductor.

n-type and p-type materials may comprise a variety of semiconductingmaterials, and all are contemplated by this disclosure. However, invarious embodiments, an n-type material may comprise an intrinsicsemiconductor (such as Silicon, Germanium, Aluminum phosphide, Aluminumarsenide, Gallium arsenide, Gallium nitride, and the like) doped withany impurity that donates electrons (e.g., Phosphorous, Arsenic,Selenium, Tellurium, Silicon, Germanium, and the like). A p-typematerial may comprise an intrinsic semiconductor doped with any impuritythat accepts electrons (e.g., Boron, Aluminum, Beryllium, Zinc, Cadmium,Silicon, Germanium, and the like).

In operation, heat energy from the heat source 206 may be absorbed bythe first substrate 202 and rejected, or dissipated, by the secondsubstrate 204. The temperature gradient between the heat source 206 andthe heat sink 208 may drive electrons (in the n-type material) and/orholes (in the p-type material) through each material. Thus, an electriccurrent may flow in the direction of heat flow, as depicted in FIG. 2.An external electrical connection comprising a positive contact 212 anda negative contact 214 may conduct electrical current generated by TEG200 to an external circuit. In an embodiment, TEG 200 may utilize athermoelectric effect (e.g., the Seebeck effect) to convert heat energyto electrical energy, however, it will be understood by those ofordinary skill in the art that any method of converting het energy intoelectric energy may be used.

Thus, the TEG 200 (or a TEG array comprising a plurality of TEGs 200, asdescribed below) may be coupled or situated between any two surfacesbetween which a temperature gradient exists to generate electricalenergy. For instance, TEG 200 may be situated between a first “hot”surface in a jet aircraft propulsion system and a second “cool” surfaceof the propulsion system, where the terms “hot” and “cool” are simplyrelative to one another during operation and between the two, define atemperature gradient. Thus, TEG 200 may recapture heat energy generatedby a jet aircraft propulsion system

Therefore, with reference to FIG. 3, a TEG array 302 is shown. The TEGarray 302 may be electrically coupled to a power supply 304, which mayreceive the output generated by TEG array 302 to supply power to enginemounted electronics 306 (as an example). In general, TEG 200 and/or TEGarray 302 may be expected to generate any suitable voltage, current,and/or power. For example, in various embodiments, a TEG 200 may beexpected to generate between two and five Volts and between one and fourAmperes. Thus, although the electrical energy generated by a single TEG200 may be useful for certain purposes, in other circumstances, greaterelectrical output may be generated by TEG array 302.

To this end, the TEG array 302 may comprise a plurality of sets of TEGs,e.g., sets 308, 310, and 312. Set 308 may comprise TEGs 308 a-308 d. Set310 may comprise TEGs 310 a-310 d. Set 312 may comprise TEGs 312 a-312d. Sets 308, 310, and 312 may be electrically coupled in parallel witheach other. Further, each of TEGs 308 a-308 d may be electricallyconnected in series with each other. Likewise, each of TEGs 310 a-310 dmay be electrically connected in series with each other, and each ofTEGs 312 a-312 d may be electrically connected in series with eachother.

In various embodiments, although three sets 308, 310, and 312 of fourTEGs 308 a-308 d, 310 a-310 d, and 312 a-312 d each are shown, anynumber of TEGs may be coupled in series, and any number of sets ofseries coupled TEGs may be coupled in parallel to form a TEG array. Invarious embodiments, and as explained in additional detail below, sixTEGs may be electrically coupled in series. In addition, in variousembodiments, six sets of series coupled TEGs may additionally form a TEGarray.

Voltage adds in series coupled voltage sources. Therefore, in operation,TEG array 302 may generate an output voltage that is the sum of thevoltages generated by a particular set of series coupled TEGs (e.g., anyof sets 308, 310, or 312). Thus, assuming an output voltage per TEG ofapproximately four to five Volts, a set of four TEGs coupled in seriesmay be expected to produce between sixteen and twenty Volts. Similarly,a set of six TEGs coupled in series may be expected to produce betweentwenty-four and thirty Volts. In various embodiments, a TEG array 302coupled in series may be expected to produce approximately twenty-eightVolts. However, a variety of other voltages may be achieved, dependingupon the TEG selected, the number of TEGs, temperature differential, andthe like.

Current adds in parallel coupled voltage sources. Therefore, inoperation, a TEG array 302 may generate an output current that is thesum of each of the sets 308, 310, and 312 of TEGs. Assuming an outputcurrent of between one and four Amps, the TEG array 302 may be expectedto produce between three and twelve Amps of current. However, a varietyof other amperages may be achieved, depending upon the TEG selected, thenumber of TEGs, temperature differential, and the like.

Approximately ten to fifty Volts (e.g., twenty-eight Volts), two totwenty amps, and fifty to five-hundred Watts may be typically requiredto power the electrical systems associated with an aircraft propulsionsystem 100. Typically, an alternator (e.g., a permanent magnetalternator or “PMA”) is used to generate the electrical output needed topower the electrical systems associated with an aircraft propulsionsystem 100. The PMA is situated within a gearbox within aircraftpropulsion system 100. Thus, the mechanical energy generated by aircraftpropulsion system 100 is used to operate the PMA. This, in turn, leachesmechanical energy from aircraft propulsion system 100. In addition, thePMA adds weight to the overall aircraft propulsion system 100 and adds amechanical load to the total load on the gearbox.

Thus, a TEG array (e.g., array 302) may be added to the aircraftpropulsion system 100, as needed and/or where possible to recapture heatenergy generated by the aircraft propulsion system 100. In variousembodiments, a TEG array, such as the array 302 may be implemented togenerate all or a portion of the electricity needed to operate theelectrical systems associated with aircraft propulsion system 100. Wherea TEG array generates all the electricity needed, a PMA may bealtogether excluded from the aircraft propulsion system 100. Similarly,where a TEG array generates only a portion of the voltage and currentneeded to power aircraft propulsion system 100, a PMA sized for a muchlower (than typical) current draw may be implemented, thereby reducingthe overall weight of the power generation system.

Thus, TEG array 302 may be added to a propulsion system 100 to achieve avariety of advantages. Among these advantages, a TEG array 200 may saveweight (in that the PMA may be removed from aircraft propulsion system100 or reduced in size), reduce load, recapture what would otherwiseconstitute wasted heat generated by the system 100, reduce a mechanicalload on the gearbox, and add reliability to aircraft propulsion system100. With respect to the last advantage (reliability), TEGs 200, whichare solid state devices, do not include moving parts and are, ingeneral, considered quite reliable. Thus, a TEG 200 may offer areliability advantage of a moving or rotating power generating assembly,such as a PMA.

Any suitable portion of aircraft propulsion system 100 may be equippedwith a TEG array 302. For example, any portion of aircraft propulsionsystem 100 in which a temperature gradient exists between a firstportion of aircraft propulsion system 100 and a second portion ofaircraft propulsion system 100 may be equipped with a TEG array 302.Several example portions of aircraft propulsion system 100 which may beequipped with a TEG array 302 are shown in FIGS. 4, 5, and 6.

With reference to FIG. 4, an exhaust portion of aircraft propulsionsystem 100 may be equipped with a TEG array 302. Specifically, a TEGarray may be placed in contact with or coupled to the IFS 104 toward anaft (exhaust) portion of the IFS 104, e.g., the exhaust nozzle 402. Thetemperature gradient between the exhaust gas 108 and the bypass airflow112 may be significant. Thus, placement of the TEG array 302 on theexhaust nozzle 402 separating these flows may result in significantenergy production.

With reference to FIG. 5, an air inlet 114 may be equipped with a TEGarray 302. As shown, the air inlet 114 (in cross-section) may beequipped with a TEG array. As described herein, an air inlet 114 mayinclude an anti-ice system, which may heat the air inlet substantiallyto melt ice that develops around the air inlet 114. The air entering theair inlet 114 is ambient air. Thus, a large temperature gradient mayexist between the air inlet 114 and incoming air, making the air inlet(in particular the anti-ice portion of the air inlet 114) a suitablelocation for placement of a TEG array 302.

With reference to FIG. 6, an IFS 104 may be equipped with a TEG array302. As described herein, the IFS 104 may be disposed coaxially about anengine core, which may operate at extremely high temperatures. Thenacelle 102 may surround the IFS 104, and cooler bypass air may flowover the outer surface of the IFS 104. Thus, a significant temperaturegradient exists between the outer surface of the IFS 104 and the bypassairflow flowing around the IFS 104. Accordingly, a TEG array 302 maygenerate significant electrical power in this area of the aircraftpropulsion system 100.

Further, and more generally as described herein, a TEG array 302 may besuitably equipped on any portion of aircraft propulsion system 100 thatexperiences a temperature gradient. For instance, in addition to theexamples discussed above, TEG arrays 302 may be placed on any hot bleedair ducts (e.g., the exhaust duct), on any engine coolers (e.g., on anyair cooled or oil cooled surface of cooling system), between a heatblanket and an inner surface of the nacelle 102, on an outer surface ofa heat blanket mounted to an inner surface of the nacelle 102, and thelike.

Benefits, other advantages, and solutions to problems have beendescribed herein with regard to specific embodiments. Furthermore, theconnecting lines shown in the various figures contained herein areintended to represent exemplary functional relationships and/or physicalcouplings between the various elements. It should be noted that manyalternative or additional functional relationships or physicalconnections may be present in a practical system. However, the benefits,advantages, solutions to problems, and any elements that may cause anybenefit, advantage, or solution to occur or become more pronounced arenot to be construed as critical, required, or essential features orelements of the inventions. The scope of the inventions is accordinglyto be limited by nothing other than the appended claims, in whichreference to an element in the singular is not intended to mean “one andonly one” unless explicitly so stated, but rather “one or more.”Moreover, where a phrase similar to “at least one of A, B, or C” is usedin the claims, it is intended that the phrase be interpreted to meanthat A alone may be present in an embodiment, B alone may be present inan embodiment, C alone may be present in an embodiment, or that anycombination of the elements A, B and C may be present in a singleembodiment; for example, A and B, A and C, B and C, or A and B and C.Different cross-hatching is used throughout the figures to denotedifferent parts but not necessarily to denote the same or differentmaterials.

Systems, methods and apparatus are provided herein. In the detaileddescription herein, references to “one embodiment”, “an embodiment”,“various embodiments”, etc., indicate that the embodiment described mayinclude a particular feature, structure, or characteristic, but everyembodiment may not necessarily include the particular feature,structure, or characteristic. Moreover, such phrases are not necessarilyreferring to the same embodiment. Further, when a particular feature,structure, or characteristic is described in connection with anembodiment, it is submitted that it is within the knowledge of oneskilled in the art to affect such feature, structure, or characteristicin connection with other embodiments whether or not explicitlydescribed. After reading the description, it will be apparent to oneskilled in the relevant art(s) how to implement the disclosure inalternative embodiments.

Furthermore, no element, component, or method step in the presentdisclosure is intended to be dedicated to the public regardless ofwhether the element, component, or method step is explicitly recited inthe claims. No claim element herein is to be construed under theprovisions of 35 U.S.C. 112, sixth paragraph, unless the element isexpressly recited using the phrase “means for.” As used herein, theterms “comprises,” “comprising,” or any other variation thereof, areintended to cover a non-exclusive inclusion, such that a process,method, article, or apparatus that comprises a list of elements does notinclude only those elements but may include other elements not expresslylisted or inherent to such process, method, article, or apparatus.

1. An aircraft jet propulsion system comprising: a thermoelectricgenerator array (“TEG” array) coupled to a portion of the aircraft jetpropulsion system, wherein the TEG array converts heat energy toelectrical energy, wherein the electrical energy is supplied to anaircraft propulsion system.
 2. The aircraft jet propulsion system ofclaim 1, further comprising an alternator that generates less energythan is associated with the electricity for operating the aircraft jetpropulsion system.
 3. The aircraft jet propulsion system of claim 2,wherein the TEG array supplements the energy generated by thealternator.
 4. The aircraft jet propulsion system of claim 3, whereinthe energy generated by the TEG array and the energy generated by thealternator are sufficient to electrically power the aircraft jetpropulsion system.
 5. The aircraft jet propulsion system of claim 1,wherein the electrical energy generated by the TEG array is sufficientto electrically power the aircraft jet propulsion system.
 6. Theaircraft jet propulsion system of claim 1, wherein the TEG array iscoupled to an exhaust portion of the aircraft jet propulsion system. 7.The aircraft jet propulsion system of claim 6, wherein the exhaustportion is an exhaust nozzle.
 8. The aircraft jet propulsion system ofclaim 1, wherein the TEG array is coupled to an outer surface of aninner fixed structure (“IFS”).
 9. The aircraft jet propulsion system ofclaim 1, wherein the TEG array is coupled to an inner surface of anacelle.
 10. The aircraft jet propulsion system of claim 1, wherein theTEG array is coupled between a heat blanket and an inner surface of anacelle.
 11. The aircraft jet propulsion system of claim 1, wherein theTEG array is coupled to an outer surface of a heat blanket mounted to aninner surface of a nacelle.
 12. The aircraft jet propulsion system ofclaim 1, wherein the TEG array is coupled to an air inlet.
 13. Theaircraft jet propulsion system of claim 12, wherein the TEG array iscoupled to an air inlet outboard of an anti-ice system.
 14. The aircraftjet propulsion system of claim 1, wherein the TEG array comprises aplurality of thermoelectric generators (“TEGs”) electrically coupled inseries.
 15. The aircraft jet propulsion system of claim 1, wherein theTEG array comprises a plurality of sets of TEGs, each set electricallycoupled in parallel.
 16. The aircraft jet propulsion system of claim 1,wherein the TEG array comprises six sets of TEGs, each set electricallycoupled in parallel.
 17. The aircraft jet propulsion system of claim 1,wherein the TEG array comprises six TEGs coupled in series.
 18. Theaircraft jet propulsion system of claim 1, wherein the TEG arraygenerates approximately 28 Volts.
 19. A thermoelectric generator array(“TEG” array) comprising: a first set of thermoelectric generators(“TEGs”) coupled in series; and a second set of TEGs coupled in series,wherein the first set of TEGs and the second TEGs are coupled inparallel, wherein the TEG array recaptures heat energy generated by aturbofan engine.